1. Field of the Invention
The present invention relates to a magnetic head bar holding unit, a lapping device, and a method of lapping medium-opposing surface (ABS) in a thin-film magnetic head.
2. Related Background Art
In general, a head gimbals assembly (HGA) is constructed by attaching a head slider formed with a thin-film magnetic head to a leading end of a flexible arm member such as a suspension. This head gimbals assembly is built in a hard disk drive (HDD) and carries out recording/reproducing to a hard disk that is a recording medium. At the time of recording/reproducing, an airflow that accompanies the rotation of the hard disk passes under the thin-film magnetic head, thereby levitating the magnetic head from the hard disk. As the recording density on the hard disk increased, the gap between the thin-film magnetic head and the hard disk, i.e., head flying height, has decreased to 10 nm, which currently seems to be the limit.
Under such circumstances, in a combination thin-film magnetic head in which a magnetoresistive device for reproducing and an inductive electromagnetic transducer for recording are laminated in this order on a support, a coil constituting the electromagnetic transducer will generate heat when the inductive electromagnetic transducer is energized. Then, the thin-film magnetic head will thermally expand in the vicinity of the electromagnetic transducer on a surface opposing a recording surface of the hard disk in the thin-film magnetic head, i.e., medium-opposing surface (ABS; Air Bearing Surface), thereby projecting toward the hard disk. As a consequence, the gap between the thin-film magnetic head and the hard disk may decrease, thereby causing the thin-film magnetic head and hard disk to come in contact with each other. Therefore, the flying height of the thin-film magnetic head must be kept such that the thin-film magnetic head and hard disk do not come in contact with each other even when the vicinity of the electromagnetic transducer thermally expands. Hence, fully achieving low levitation for a thin-film magnetic head has been difficult.
Known examples of techniques for achieving lower thin-film magnetic head levitation by preventing the occurrence of such a state include partly shaving the leading end part of the overcoat layer on the medium-opposing surface of the thin-film magnetic head to yield a step, and designing the coil constituting the electromagnetic transducer to have a glass transition temperature of about 70 to 100° C., thereby lowering Young's modulus, and reducing the thermal stress occurring in the coil part (see, for example, Japanese Patent Application Laid-Open No. 2000-306215).